Root Spiraling Research Articles

Radicle length and container size effects on root deformities in the Mediterranean oak <i>Quercus suber</i> L.

The aim of this study was to assess the effects on root deformations in Mediterranean cork oaks Quercus suber L. of container size and radicle length at the time of sowing. Acorns at five sowing methods – intact acorns, acorns that had germinated during storage, acorns that had germinated after moist stratification and acorns with radicles (R) less than 5 mm in length, 7 mm to 12 mm in length and more than 15 mm length – were planted individually in WM type containers of 400 cm3, 800 cm3 and 1,200 cm3. At the end of the nursery growth period, the roots of the 1,080 sampled seedlings were examined for root deformities. The experiment results showed that root deformation affected almost half (49%) of the container-grown cork oak seedlings and that the germination status of acorns at the time of planting had a significant effect on root deformations, whereas container volume had no clear effect. The largest number of deformed roots (91%) was observed in seedlings grown from germinated acorns, as compared to 9% of seedlings grown from intact acorns. Planting germinated acorns with radicles 15 < R < 20 mm and 7 < R < 12 mm in length produced the highest percentages of detrimental deformations. Irrespective of size, the bottomless WM container type was shown to be highly effective against the root spiralling frequently observed in closed cylindrical polyethylene bags. The results of this study could help to improve cork oak seedling quality for more successful reforestation programs.

Bottles to trees: Plastic beverage bottles as an alternative nursery growing container for reforestation in developing countries.

Reforestation is needed globally to help restore degraded sites, combat desertification, protect watersheds, and provide forest products. This involves planting forest tree seedlings grown in local nurseries, but technologies to produce quality seedlings are lacking in developing countries. Modern nursery containers used to propagate seedlings have internal-surface barriers (ribs or ridges) or side-slits to prevent root spiraling. These are cost prohibitive or unavailable in developing countries and so polybags (plastic bags) are more commonly used, despite their tendency to produce seedlings with deformed root systems that have less potential to establish on field sites. Discarded plastic bottles, which are readily available worldwide, may be a feasible alternative for seedling propagation. We conducted two experiments to assess the potential of repurposed plastic beverage bottles to grow quality trees: 1) Container Comparison–to evaluate Arizona walnut (Juglans major [Toor.] Heller) and Afghan pine (Pinus eldarica Medw.) seedling root and shoot development in two plastic bottle types compared to modern nursery containers and polybags, and 2) Bottle Modification–to examine the effects of root spiraling prevention techniques (side-slits, internal-ridges, and control) and container opacity (green, black, and clear) on Afghan pine seedling morphological attributes. Nursery growth and first-year seedling field performance were evaluated for both experiments. In experiment one, seedlings of both species had fewer spiraled roots in bottle containers compared to polybags. Arizona walnut had more fibrous root systems in polybags, while Afghan pine root system fibrosity was greatest in bottle containers. First-year field performance of both species was not affected by container type. In experiment two, less spiraled roots occurred in containers with air-slits and interior-ridges compared to the control. The effects of container opacity on seedling morphology were inconsistent. Root spiral prevention and opacity had no influence on Afghan pine one-year survival, field height and diameter, with the exception of opacity for height growth, whereby seedlings grown in green containers were taller than those grown in black containers, but seedlings grown in clear containers were similar to both. Our results provide the first evidence that plastic bottle containers may provide an effective alternative for production of high quality seedlings, which may benefit agroforestry, reforestation, restoration, and conservation programs in developing countries.

Effects of copper root pruning and radicle pruning on first-season field growth and nutrient status of Chinese cork oak seedlings

Root deformation is a common challenge in container seedlings especially for vigorous-rooted tree species. The issue is significant for Chinese cork oak (Quercus variabilis Blume.) which is grown in cost-effective polybags. In this study we examined how copper root pruning and radicle pruning (1/3 or 2/3 of radicle length) individually and together (1/3 radicle pruning in combination with copper root pruning) affected root architecture, growth and nutrient storage of nursery seedlings, and survival, growth performance and nutrient status during the first outplanting season. Copper root pruning failed to reduce root spiraling, and decreased total root length and surface area by decreasing root length and surface area of roots with diameter <5 mm. In contrast, radicle pruning decreased root deformation and induced taproot formation. However, intensity of radicle pruning impacted seedling size at planting and 2/3 radicle pruning decreased height and stem dry mass relative to the control. Root effects of combination (radicle plus copper root pruning) treatment on root development were not superior to 1/3 radicle pruning. Combination treatment decreased roots with diameter <2 mm. Overall 1/3 radicle pruning has the best potential to modify root development for vigorous-rooted Chinese cork oak seedlings grown in polybags.

INTRODUCTION OF ROOT TRAINERS TO FOREST NURSERIES IN SRI LANKA

Use of poly bags for the production of tree seedlings result in several disadvantages due todistortion of the root system. Poor lateral root formation, root spiralling and bending of taproot occurs in poly bags and affects the growth of the tree. Slow growth, poor draughttolerance and lack of wind firmness are some of the major problems resulting from the useof poly bagsA new container called root trainer has been developed to overcome these problems.Root trainers were introduced to the forest research centre nursery at Kumbalpola with aview to gain first hand experience on the handling maintenance and preparation of pottingmedia. The results have been encouraging. A good potting media suitable for the use inroot trainers was developed. Better root growth was observed in root trainer grownseedlings. Maintenance, handling and field planting were much easier compare to polybag grown seedlings. It is concluded that the root trainers can be successfully used for theproduction of tree seedlings.

Container characteristics influence Pinus pinea seedling development in the nursery and field

The growth and development of Pinus pinea seedlings grown in different containers was followed through one growing season in the nursery and 3 years following outplanting in the field. The variables studied in the nursery were height, diameter, biomass of shoots and roots, nutrient uptake and root density. The measured field variables, height and diameter increment and survival, were correlated with the nursery variables. Container volume had the greatest influence on plant morphology. Containers with larger rooting volume had seedlings with larger height and diameter, greater nutrient content, and better field performance. Growing density was correlated with seedling morphology and nutrient concentration in the nursery. Among the variables that influenced container volume, the diameter of the container was the most important, while the depth of the container had a minor influence on seedling morphology. The best indicator of seedling development in the nursery was the ratio of container depth to container diameter, and the optimum ratio was 4. All containers produced seedlings with some root spiralling, including those containers with ribs. There was no relationship between either the number of spiralling roots or the angle of spiralling and container characteristics. Furthermore, root spiralling did not influence seedling performance following outplanting. Root density (root biomass/cm 3) was inversely correlated with container volume but there was no correlation with either depth or growing density. The largest plants were produced with container volumes of 300–400 cm 3, depth/diameter ratios of 4, and growing densities of 200–300 seedlings/m 2. These growing conditions will result in larger Pinus pinea seedlings coming out of the nursery, which will increase growth following outplanting.

Slits in container wall improve root structure and stem straightness of outplanted Scots pine seedlings

Root structure and basal sweep were measured on 6-year-old Scots pine (Pinus sylvestris L.) trees at two sites with different soil fertility. Each site was planted with seedlings of identical origin after nursery cultivation in either solidwall container types with vertical ribs or in slitwall container types. Neither container design nor container volume affected tree height or stem diameter on the two sites. The transversal area of lateral roots was larger than the transversal area of bottom roots for the two container types at both sites. The proportion of bottom root transversal area to the total root transversal area was larger in the seedlings growing on the low fertility site than in those growing in the high fertility site for both container types. Seedlings cultivated in slitwall containers had a larger root area in proportion to stem diameter and had less root spiralling compared to the trees cultivated in solidwall containers. At the high fertility site, trees from the slitwall container type had straighter stem bases than seedlings grown in solidwall containers. At the low fertility site, differences in basal sweep formation were small between the container types. Reasons for this are discussed.

Copper coated polybags improve seedling morphology for two nursery-grown Mexican pine species

Root spiraling, root egression through drainage holes, and poor growing medium drainage are common problems in polybag seedling production systems in Mexico. Two commercially and environmentally important Mexican conifer species, Pinus pseudostrobus Lindi. and Pinus montezumae Lamb., were grown in simulated Mexican “platabanda” nursery conditions. The seedlings were grown in polybag containers, with and without chemical root pruning and with six different drainage designs. A chemical root pruning product, Spin Out ®, was evaluated on these two pine species. Six different drainage designs ranging from an open-bottom, well-drained design, to small holes and restricted drainage were tested. The results clearly demonstrated benefits from the chemical root pruning, but the impact of the drainage treatments was distorted by the use of a well-drained growing medium. Root collar diameter, shoot dry weight, and root dry weight were increased in Spin Out ®-treated seedlings. These seedlings also had significantly fewer roots egressing from the bag and spiraling at the bottom of the polybag. Generally, Spin Out ®-treated seedlings had a more fibrous and well-developed root system than untreated seedlings. Chemical root pruning can be used to reduce or eliminate root deformations and improve seedling quality of these two Mexican pines.

Incident Irradiance and Cupric Hydroxide Container Treatment Effects on Early Growth and Development of Container-grown Pawpaw Seedlings

The North American pawpaw [Asimina triloba (L.) Dunal] has great potential as a fruit crop or as a landscape plant. The influence of incident irradiance on pawpaw seedling growth and development in containers was examined in the greenhouse and outdoors. Root spiraling can be a problem for container-grown pawpaw seedlings; therefore, the influence of paint containing cupric hydroxide [Cu(OH)2] at 100 g·L-1 applied to the interior of containers on plant growth was also examined in a greenhouse environment. In pawpaw seedlings grown outdoors for 11 weeks, low to moderate shading levels of 28%, 51%, or 81% increased leaf number, total leaf area, and total plant dry weight (DW) compared to nonshaded seedlings. A shading level of 81% decreased the root to shoot ratio by half compared to nonshaded plants. Shading of 98% reduced leaf number, leaf size, and shoot, root, and total plant DW. Shading increased leaf chlorophyll a and b concentrations for pawpaw seedlings grown outdoors, while it decreased average specific leaf DW (mg·cm-2). In a separate greenhouse experiment, pawpaw seedlings subjected to shade treatments of 0%, 33%, 56%, 81%, or 98% did not respond as greatly to shading as plants grown outdoors. Greenhouse-grown plants had greater total and average leaf area under 33% or 56% shading than nonshaded plants; however, shading &gt;56% reduced root, shoot, and total plant DW. Total shoot DW was greater in greenhouse grown plants with 33% shading compared to nonshaded plants. Pawpaw seedlings in control and most shade treatments (33% to 81%) in the greenhouse environment had more leaves and greater leaf area, as well as larger shoot, root, and total plant DW than seedlings in similar treatments grown outdoors. The greenhouse environment had a 10% lower irradiance, a 60% lower ultraviolet irradiance, and a significantly higher (1.23 vs. 1.20) red to far-red light ratio than the outdoors environment. Treatment of container interiors with Cu(OH)2 decreased total and lateral root DW in nonshaded seedlings, and it adversely affected plant quality by causing a yellowing of leaves and reduction of chlorophyll levels by the end of the experiment in shaded plants. Growth characteristics of pawpaw seedlings were positively influenced by low to moderate shading (28% or 51%) outdoors and low shading (33%) in the greenhouse. Seedlings did not benefit from application of Cu(OH)2 to containers at the concentration used in this study. Commercial nurseries can further improve production of pawpaw seedlings using low to moderate shading outdoors.

Early Growth and Development of Pawpaw [Asimina triloba (L.) Dunal] Seedlings in the Greenhouse as Influenced by Shade and Root-zone Modification

This experiment was designed to determine the optimal light level for growing pawpaw seedlings in the greenhouse. In addition, we wanted to determine if modifying the root-zone would positively impact pawpaw seedling growth and development. Experimental treatments were imposed from seed sowing until the plants were destructively harvested. The experimental design was a split-plot, where blocking was done by position in the greenhouse. The main plot of the experiment was shade. This was accomplished by growing seedlings under a wooden frame covered with shadecloth to reduce incident light intensity received by the plant by 30%, 55%, 80%, or 95%. The control treatment was 0% shade or ambient greenhouse light level. The split-plot was root-zone modification. Half of all growing containers were untreated (control) while the other half were painted with SpinOut™, a commercially available product used to reduce root spiraling in nursery containers. There were 40 replicate seedlings per experimental treatment combination per block. Seedling shoot length and unfolded leaf number was recorded twice a week from seedling emergence until destructive harvest. Whole-plant leaf area was also determined. Leaves, stems, and tap and lateral roots were separated and dried to determine biomass partitioned to the respective organs. Up to 55% shade did not significantly reduce whole-plant biomass, while plants at 80% and 95% shade were stunted. Shade in the greenhouse is not required as was previously thought. Specific leaf mass and lateral root mass decreased as shade increased. Neither tap or lateral root dry weights were significantly affected by root-zone modification. New recommendations for container production of pawpaws in the greenhouse will be discussed.

Copper-treated Plug Flats Influence Root Growth and Flowering of Bedding Plants

A copper hydroxide formulation (0%, 3.5%, 7%, 11% Cu) was applied to plug trays before sowing seeds of Impatiens ×hybrida L. `Accent Red', Pelargonium ×hortorum Bailey `Scarlet Elite', and Petunia ×hybrida Hort.Vilm.-Andr. `Ultra White' to investigate the influence of the formulations on ease of transplant, root growth, and shoot growth. These factors also were investigated in Cu-treated seedling plugs held past optimal transplanting stage. Root spiraling and seedling height at transplant were reduced for all taxa grown in Cu-treated trays, regardless of concentration, compared to seedlings from nontreated trays. Root weight and shoot weight responses to Cu treatments at transplant and at flowering varied among taxa. Mature heights of all taxa were unaffected by Cu treatment; however, flowering date was delayed for impatiens and geraniums transplanted at optimal time from Cu-treated trays. In general, petunias displayed little response to Cu treatment. Root spiraling was reduced and plugs were removed more easily from Cu-treated than from control trays stored for 2 weeks in the greenhouse, but flowering time was delayed for 12 days for impatiens and petunias and 21 days for geraniums, regardless of Cu concentration.

Survival and growth of four amabilis fir stock types on Vancouver Island

Four stock types of amabilis fir (Abies amabilis) planted on Vancouver Island were compared for root growth capacity and field performance. Initial root growth capacity ratings and field performance of the stock types after five years differed significantly. Ranking the stock types by decreasing survival, stem height and diameter: 1 + 1 PBR 211 (89.4%, 78 cm, 15.7 mm), 1 + 0 PSB 313 (79.7%, 73 cm, 13.8 mm), 1 + 0 PSB 211 (76.8%, 66 cm, 12.9 mm) and 2 + 0 BR (58.9%, 59 cm, 11.0 mm). Given current nursery and planting costs and survival rates, the 1 + 0 PSB 313 and 211 are least expensive reforestation options, the 2 + 0 BR and 1 + 1 PBR 211 the most expensive. Root form of samples of each stock type lack well developed tap and lateral roots with root spiralling evident in the styroblock stock. Key words: Amabilis fir, stock types, bareroot, styroblock plugs

Root System Structure in Planted and Seeded Loblolly and Shortleaf Pine

Abstract Differences in root system structure attributable to stand origin were examined by pairing seeded and planted stands of loblolly (Pinus taeda L.) and shortleaf pine (P. echinata Mill.). The 17 paired stands were 3 to 9 years old and located in Arkansas, Oklahoma, and Texas on similar soil and site conditions. Root systems from 12 trees were excavated from each stand, classified by root system type and measured for number and size of first-order lateral roots and amount of root spiraling and bending. Although root systems of planted trees were commonly deformed, the most consistent difference in root system structure between planted and seeded trees was the increased distance from groundline to the uppermost lateral roots on planted seedlings. A linear discriminant function including this variable correctly classified all loblolly pine plots and 89% of the shortleaf pine plots as to whether the plot had been planted or seeded. Planted trees also had fewer first-order lateral roots less than 10 mm in diameter and exhibited greater spiraling and bending of major first-order laterals than seeded trees. Differences in root system structure between planted and seeded trees were similar for the two species. For. Sci. 35(2):469-480.

Chemical root pruning of Chinese pine seedlings raised in cupric sulfide impregnated paper containers

Chinese pine (Pinus tabulaeformis Carr.) seedlings were raised for 22 weeks in tubes of both plain kraft paper and kraft paper with a thin polyethylene film coating on one side. Some containers of each type were made from paper impregnated with cupric sulfide. Both copper-impregnated and untreated kraft paper decomposed completely within three months. Roots of adjacent seedlings in untreated paper tubes, without a polyethylene coating, became extensively intermeshed and could not be separated without damage. Root intermeshing did not occur among seedlings raised in tubes of untreated polyethylene coated paper, but the polyethylene barrier caused root spiralling. Although impregnating the containers with cupric sulfide did not prevent paper decomposition, it prevented root spiralling in paper tubes with a polyethylene coating, and root intermeshing by adjacent seedlings in paper tubes without a polyethylene coating.

Comparative root system morphologies of seeded-in-place, bareroot, and containerized Douglas-fir seedlings after outplanting

Root systems of 5- to 8-year-old Pseudotsugamenziesii (Mirb.) Franco seedlings of natural, bareroot, and container origin were quantitatively analyzed to determine the effects of seedling source on root system morphology. Lateral root orientation was stressed.Container and planting constrictions on root system morphology were recognizable after outplanting; planted stock types were differentiated from seeded-in-place seedlings on the basis of root system morphology. Container and natural seedlings had less variation in root system morphology within stock type than bareroot stock. Root spiraling was so low in the Douglas-fir stock types studies that it is not likely to affect tree stability. There was no overall effect of root system morphology on height of seedlings around 6 years of age.